A 99-Percent Solution to Stop Mass-Murders

I agree fully with this article.
When am I breaking the law? Before I carry my EDC concealed into a "Gun Free" or after I shoot the mass murderer? Or is the proprietor violating my 2nd Amendment Rights and thus breaking the law of the land?
"ASKING FOR A FRIEND".

My thought is that Criminals will be criminals and whether they take out one victim or 30 victims, we can't stop every criminal before they act.
What can be done is minimizing the affects of criminals and mass shootings if Constitutional carry were authorized. I live in Missouri, and we see people open carry all the time here. It's not uncommon to walk through the grocery store and see someone with a sidearm on their hip. . . . and there is no telling how many have weapons hidden under their shirts.

I agree, but would like to add a suggestion. When a person gets assaulted wether it's on the street or in a school hallway, it's a crime and the assailant needs to be prosecuted. Recently it was reported a young female student was attacked in school by more than one person and later committed suicide. The school responded it wasn't their policy to expell students so the attackers were given a good talking to and sent on to class. While they didn't actually murder the girl, they did physically assault her and without question should have been arrested. How many of the mass murderers the article refers to suffered this kind of treatment?